In 2006, a story appeared in the newspapers, courtesy of Jeremy Paxman, who had been staying at Sandringham while researching his latest book, On Royalty. The gist of it was that the Prince of Wales was so fussy about his soft-boiled eggs that his staff would prepare up to seven for him every morning in the hope that at least one would be done to perfection.

When I first heard this, I clapped my hands together in glee. It seemed so perfect, so of a piece with what one already believed of Charles (unable even to put his own toothpaste on his toothbrush). Soon after, though, there came – boo! – a rebuttal. No, said a spokesman for Clarence House. Paxman's anecdote was "totally untrue". The Prince of Wales would eat his egg irrespective of whether or not its yolk was sufficiently runny. As denials go, this one was swift, and absolute. But it was also, to my mind, a failure. For one thing, it implicitly suggested that Charles thought himself quite the hero for ploughing manfully through a hard, dry egg. For another, more egg stories soon followed in its wake. Two years later, Mervyn Wycherley, Charles's private chef during his first marriage, revealed that the prince's security detail would inform the kitchen as soon as HRH was on his way home for tea. "His eggs had to be boiled for exactly four minutes," said Wycherley. "It was never anything other than a four-minute egg. His detectives radioed his ETA ahead. I always kept three pans boiling – just to be safe."

What is it with the royal family and eggs? If we are to believe Charles Oliver, a servant who worked at Buckingham Palace under Victoria, George VI and Queen Elizabeth II, and whose "lost" diaries were eventually used, in 2003, as the basis for a rather odd book called Dinner at Buckingham Palace, the royals have a "passion" for them. Like the rest of us, they like them scrambled, fried, boiled and poached, but they also enjoy them en cocotte à la crème (baked with cream, a treat they like to accompany with minced chicken); plat chasseur (garnished with chicken livers and a sauce of white wine, consommé and herbs); and farcis à la Chimay (stuffed with mushrooms and coated with Mornay sauce). Every day begins with an egg, and they're eaten for tea, too – with crumpets, if you're Prince Charles. The Queen favours brown eggs, believing that they taste better. Her great-great grandmother, Queen Victoria, ate her boiled egg, served in a golden egg cup, with a golden spoon.

Leaving aside the indelicate fact that constipation must surely be endemic in the royal palaces, this passion for eggs – such an everyday foodstuff and yet one that can be gussied up to a quite epic degree should cook be in possession of a sufficiently old-fashioned recipe book and large quantities of gelatin – pretty much sums up the royal family's attitude to food. The modern royals, by which I mean Victoria onwards, have often managed to combine an unbounded extravagance with a certain ersatz asceticism.

Queen Victoria, who was convinced that "things taste better in smaller houses", favoured plain food, a fact that set her against the fashion of the day, when French cuisine was all the rage (she had a French chef herself, in the form of Charles Elmé Francatelli, until he hit a maid and was dismissed). At home, she favoured pies and invalid soups – pearl barley or potato – washed down with her favourite drink, a mixture of claret and whisky.

On the other hand, when she visited Hatfield House, the home of the Marquess of Salisbury, in 1846, her host felt obliged to spend some £75,000 (at today's prices) on food and drink for a three-day visit (£800 on turtle soup alone). She believed, too, in keeping an "imperial" table: one commensurate with her great nation's place in the world. Dinners were elaborate, and, at lunch, curry and rice were always available, served by two Indian servants in elaborate uniforms of blue and gold.

Admittedly, these things do sometimes skip a generation. While he waited to become king, her son, Edward, the Prince of Wales, developed more lavish tastes. Abstemious he most certainly was not. A cooked breakfast would be accompanied by roast chicken and lobster salad to tide him over until lunch, which would itself consist of eight courses. This was followed by high tea, and then a dinner of 12 courses: two kinds of soup, whole salmons and turbots, vast saddles of mutton and sirloins of beef, not to mention several game birds, some devilled herrings and plenty of cheese. Finally, before bedtime, he would squeeze in a light supper of cakes and savouries. Edward, the playboy king, was so greedy that, at the theatre or opera, he would insist on an hour-long interval in order that he might take his supper in the royal box. Six heaving hampers of food – plovers' eggs, cold trout, Parisian pastries – would duly be delivered by the palace.

George V was more modest: before he came to the throne, he lived in the relatively low-key York Cottage, on the Sandringham estate. It was decorated with new furniture, not old, as if he and his bride, the future Queen Mary, were just an ordinary middle-class couple, and he passed his time mostly in killing animals and tending his stamp collection. So when the First World War broke out, four years into his reign, it was perhaps unsurprising that Mary insisted on rationing in the palace – by some accounts even before the public was subjected to it. No one, according to her edict, was to eat more than two courses for breakfast, and the royal chefs were encouraged to create mock cutlets from minced meat. For his part, George prohibited the drinking of wine as long as the war lasted, and was happy to eat thin soup for elevenses, and mashed potato with everything.

Such deft PR continued with George VI, who also observed rationing during the Second World War. But George was married to Queen Elizabeth, the Queen Mother – a woman more royal than the royals. Last year, a collection of recipes by former staff and guests at the Queen Mother's Scottish house, the Castle of Mey, was published, with a foreword by her ever-devoted grandson, Prince Charles – and just reading it is enough to make the arteries harden.

Elizabeth loved After Eight ice cream (to make quantities for six people you will need two boxes of After Eights and no fewer than six egg yolks), the Soufflé Rothschild created by Carême (its essential ingredient is Goldwasser, a strong liqueur containing flakes of gold leaf) and – what did I tell you about eggs? – Oeufs Drumkilbo, a sort of prawn-cocktail-meets-eggs-mayonnaise dish which she liked to serve on picnics. (Drumbilko is the next estate to Glamis Castle, the Queen Mother's childhood hood; this dish was also served at the wedding of Prince Andrew and Sarah Ferguson in 1986).

And so it continues, the strange coupling of decadence and moderation. The royals remind me of the friend who points out, when the bill comes, that they did not have pudding – shortly before announcing they are off to their new second home for the weekend. We know that the Queen favours Tupperware, the better to keep her breakfast cereal fresh. We know she likes Irish stew, rissoles (pheasant, preferably), and a good cup of tea. But we know, too, that every morning she writes her heart's desires in her menu book for the staff, that diners at Balmoral are piped into dinner, that footmen abound in all her homes.

The Duke of Edinburgh is said to be obsessed with barbecuing in quiet corners of his wife's estates, but is it really him who loads up the Land Rover with charcoal? And when we're told that he takes his electric frying pan everywhere, who is it, I wonder, who packs it for him? As for Prince Charles's instructions to his cook not to waste the lovage that grows tall in the Highgrove kitchen garden – it must be used for soup! – this sounds admirable only until you remember that Charles' household is 159 strong, and that his personal spending rose last year by some 50%.

How much do royal tastes influence the rest of us? Not much is the truth. Victoria and Albert might have introduced us to the Christmas tree, but we can't blame them for the turkey; they usually had beef (though on one occasion, or so I read, they enjoyed a swan). There is coronation chicken, invented by Constance Spry and Rosemary Hume for the banquet to mark the Queen's coronation in 1953 (I don't know whether the Queen likes coronation chicken herself but, made right, with poached chicken rather than leftovers, and a light dressing rather than a slick of mayonnaise and curry powder, it is delicious).

There is Prince Charles's range of organic Duchy Originals, though when you see how much HRH's oat cakes, jam and herbal tea cost, what you feel mostly is the need to run in the direction of Lidl. But very little else. If anything, they're rushing towards us these days. The Duchess of Cambridge shops at Spar, Morrison's and Waitrose – she pushes her own trolley! – and at an Anglesey butcher, where she was seen spending 82p on lamb's liver to make a gravy for a pie (contrast this with the San Lorenzo-loving Princess Diana, whose cooking skills were so limited her chef had to leave her a note explaining how to operate the microwave).

I know there are those who feel that while the most prominent family in the land continues to stalk and to shoot, blood sports will never be outlawed. But since I am not anti these things, I can't say I mind terribly much. I once went stalking in Scotland for this magazine, and the experience was so bone-achingly exhausting, I began to think Charles might be tougher than he sometimes seems.

For my own part, I associate the royal family very strongly indeed with icing. To be specific, with the bright blue and red icing I used to decorate some cakes I made with my stepmother when it was the Queen's silver jubilee. (Ah, the innocence of 1977, when all the world was one giant street party!) And with a certain kind of kitschy biscuit tin. The other day, in Marks & Spencer, I found my hand hovering for longer than it should have done over a tin of Diamond Jubilee shortbread. It was very pretty; quite understated as royal souvenirs go. I resisted, that day. But I know in my bones such a tin will eventually find its way into my shopping basket. Shortbread is always delicious – whether your attitude towards it is ironic, or not.